You can believe anything you'ld like but those trying to sell you a product will say anything to try and get their point across, even if not based on facts.
I've never heard of the "snake oil" you've linked above BUT the other guys have been around for a while, especially Mobil 1 and Amsoil.
Sythetic oils have their known benefits and many real tests have been done to support that, try going to www.amsoil.com next.
I wouldn't ever try any (especially unknown) additives in my Volvo and Volvo advises against them too. Volvo does approve many synthetic oils however.
Although I now use Amsoil myself, I can get any engine to 200K miles with petroleum oils and regular maintenance too.
Just "say no" to any additives that claim their stuff is too good to be true.